High speed communications among individual chips within products or among products require interfaces such as high speed buses, I/O (input/output) interfaces for optical links or high speed RF (radio frequency) links, or other interface structures. Integration of the several devices that comprise a product into a unitary structure eliminates the need for some of the interfaces required for signal hand off, buffering and other functions that must be accomplished in a multi-element product. Prior art fabrication techniques available for producing unitary structures involving various semiconductor materials have proven prohibitively costly and space-inefficient to yield significant improvements by unifying structures.
A unitary communication structure reduces the need for individual I/O interfaces for each module transition, and thereby eliminates the need for on-chip xe2x80x9creal estatexe2x80x9d to accommodate such I/O interfaces. Other advantages realized by a cost-efficient unitary fabrication ability include a significant reduction in size, an increase in operating speed, a reduction of electromagnetic noise and radiation emanations, an increase in performance reliability, a reduction in cost of manufacture and lower operating power requirements with an attendant lower cost of operation.
A capability for truly unitary fabrication employing a variety of semiconductor manufacturing technologies provides opportunities to produce multi-technology unitary structures that meet a wide variety of needs. For example, unitary structures may be fabricated to satisfy a wide variety of standards, such as cellular telephone standards, personal communication system (PCS) standards, xe2x80x9cBluetoothxe2x80x9d communication standards, and other industry-wide standards.
There is a need for a communication apparatus manifested in a cost-effective integrated unitary structure appropriate for high speed communications, especially for such communications involving dynamic determination of message routing.
This invention relates generally to semiconductor structures and devices for optical communication signal handling apparatuses and to a method for their fabrication. This invention more specifically relates to compound semiconductor structures and devices and to the fabrication and use of semiconductor structures, devices, and integrated circuits that include a monocrystalline compound semiconductor material.
The preferred embodiment of the present invention is an apparatus for effecting communications by a home station among a plurality of remote stations in at least one communication medium. The apparatus comprises (a) local signal receiving circuitry for receiving an originating signal at the home station, the originating signal contains local intelligence; and (b) local signal processing circuitry coupled with the local signal receiving circuitry for processing the originating signal for conveying the local intelligence via the at least one communication medium to a selected remote station of the plurality of remote stations. The local signal receiving circuitry and the local signal processing circuitry are implemented in a unitary structure borne upon a single silicon substrate. The apparatus may further comprise (c) remote signal receiving circuitry for receiving a transmitted signal at the home station, the transmitted signal containing remote intelligence; and (d) remote signal processing circuitry coupled with the remote signal receiving circuitry for processing the transmitted signal for conveying the remote intelligence to a user. The remote signal receiving circuitry and the remote signal processing circuitry are preferably implemented in the unitary structure.
The method of the present invention preferably comprises the steps of: (a) providing an apparatus according to the unitary structure described above implemented in a unitary structure borne upon a single silicon substrate; (b) providing information processing circuitry for dynamically determining ad hoc network routing among the plurality of remote stations for establishing communications with at least one target remote station of the at least one selected remote stations not in direct communication with the home station. The information processing circuitry is preferably implemented in the unitary structure. The method proceeds with the steps of (c) ascertaining input capabilities and output capabilities of the home station; (d) polling the at least one selected remote station to ascertain network capabilities of the at least one selected remote station; (e) defining at least one primary network route among the at least one selected remote station for communicating with the at least one target remote station; and (f) conveying the local intelligence via the at least one communication medium to the at least one selected remote station using the at least one primary network route.
The vast majority of semiconductor discrete devices and integrated circuits employed for communications, including high-speed communications, are fabricated from silicon, at least in part because of the availability of inexpensive, high quality monocrystalline silicon substrates. Other semiconductor materials, such as the so called compound semiconductor materials, have physical attributes, including wider bandgap and/or higher mobility than silicon, or direct bandgaps that makes these materials advantageous for certain types of semiconductor devices. Unfortunately, compound semiconductor materials are generally much more expensive than silicon and are not available in large wafers as is silicon. Gallium arsenide (GaAs), the most readily available compound semiconductor material, is available in wafers only up to about 150 millimeters (mm) in diameter. In contrast, silicon wafers are available up to about 300 mm and are widely available at 200 mm. The 150 mm GaAs wafers are many times more expensive than are their silicon counterparts. Wafers of other compound semiconductor materials are even less available and are more expensive than GaAs.
Because of the desirable characteristics of compound semiconductor materials, and because of their present generally high cost and low availability in bulk form, for many years attempts have been made to grow thin films of the compound semiconductor materials on a foreign substrate. To achieve optimal characteristics of the compound semiconductor material, however, a monocrystalline film of high crystalline quality is desired. Attempts have been made, for example, to grow layers of a monocrystalline compound semiconductor material on germanium, silicon, and various insulators. These attempts have generally been unsuccessful because lattice mismatches between the host crystal and the grown crystal have caused the resulting thin film of compound semiconductor material to be of low crystalline quality.
If a large area thin film of high quality monocrystalline compound semiconductor material was available at low cost, a variety of semiconductor devices could advantageously be fabricated in that film at a low cost compared to the cost of fabricating such devices on a bulk wafer of compound semiconductor material or in an epitaxial film of such material on a bulk wafer of compound semiconductor material. In addition, if a thin film of high quality monocrystalline compound semiconductor material could be realized on a bulk wafer such as a silicon wafer, an integrated device structure could be achieved that took advantage of the best properties of both the silicon and the compound semiconductor material.
Accordingly, a need exists for a semiconductor structure that provides a high quality monocrystalline compound semiconductor film over another monocrystalline material and for a process for making such a structure.